High track drive system for track work vehicle

ABSTRACT

A track work vehicle includes an axle input shaft defining a first axis of rotation, and a differential gear case having at least one planetary gear set. The track work vehicle includes a track drive system contained, at least in part, in the differential gear case. The track drive system includes a first gear coupled to the axle input shaft and a second gear coupled to the first gear. The track drive system includes a bevel gear assembly coupled to the second gear and a bevel gear set coupled to the planetary gear set. The track work vehicle includes at least one drive axle coupled to the planetary gear set and a drive wheel for driving a continuous ground-engaging track. The drive axle has a second axis of rotation that is vertically offset from the first axis of rotation and substantially coaxial with a centerline of the drive wheel.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. application Ser. No.15/655,733, filed Jul. 20, 2017, now allowed.

STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE DISCLOSURE

This disclosure relates to work vehicles, and particularly to track workvehicles having an elevated track drive system.

BACKGROUND OF THE DISCLOSURE

Various work vehicles, such as tractors, include tracks that provideadditional traction to enable the tractors to more easily move throughrough or muddy fields. These tracks are driven by drive wheels. Incertain instances, the drive wheels are driven such that a centerline ofeach of the track drive wheels is at the same elevation as a drive axleshaft of the tractor. In other instances, in order to improveperformance, a gear set is coupled to the drive wheel external to adifferential gear case to raise an elevation of a drive axle shaft todrive the drive wheels at a higher elevation. This requires an externalgear set for each of the drive wheels, which increases part count and aweight of the track work vehicle. In addition, the multiple gear setseach require maintenance, which may reduce the productivity of the trackwork vehicle.

SUMMARY OF THE DISCLOSURE

The disclosure provides a track work vehicle having a high track drivesystem within a differential housing that elevates a portion of adrivetrain to an axis that is coaxial with a centerline of a drivewheel.

In one aspect, the disclosure provides a track work vehicle. The trackwork vehicle includes an axle input shaft defining a first axis ofrotation, and a differential gear case having at least one planetarygear set. The track work vehicle includes a track drive systemcontained, at least in part, in the differential gear case. The trackdrive system includes a first gear coupled to the axle input shaft and asecond gear coupled to the first gear. The track drive system includes abevel gear assembly coupled to the second gear and a bevel gear setcoupled to the at least one planetary gear set. The track work vehicleincludes at least one drive axle shaft coupled to the at least oneplanetary gear set and a drive wheel for driving a continuousground-engaging track. The at least one drive axle shaft has a secondaxis of rotation that is vertically offset from the first axis ofrotation and substantially coaxial with a centerline of the drive wheel.

In another aspect the disclosure provides a track work vehicle. Thetrack work vehicle includes an axle input shaft defining a first axis ofrotation, and a differential gear case having at least one planetarygear set. The track work vehicle includes a track drive systemcontained, at least in part, in the differential gear case. The trackdrive system includes a first gear coupled to the axle input shaft and asecond gear coupled to the first gear. The track drive system includes abevel gear assembly coupled to the second gear and a bevel gear setcoupled to the at least one planetary gear set. The track drive systemincludes a ring gear coupled to the bevel gear set and to the bevel gearassembly. The track work vehicle includes at least one drive axle shaftcoupled to the at least one planetary gear set and a drive wheel fordriving a continuous ground-engaging track. The at least one drive axleshaft has a second axis of rotation that is vertically offset from thefirst axis of rotation and substantially coaxial with a centerline ofthe drive wheel.

In yet another aspect the disclosure provides a track work vehicle. Thetrack work vehicle includes an axle input shaft defining a first axis ofrotation and a differential gear case having at least one planetary gearset. The track work vehicle includes a track drive system contained, atleast in part, in the differential gear case. The track drive systemincludes a first gear coupled to the axle input shaft and a second gearcoupled to the first gear. The track drive system includes a bevel gearassembly having a shaft and a bevel gear. The shaft is coupled to thesecond gear. The track drive system includes a bevel gear set coupled tothe at least one planetary gear set and a ring gear coupled to the bevelgear set and to the bevel gear. The track work vehicle includes at leastone drive axle shaft coupled to the at least one planetary gear set anda drive wheel coupled to the at least one drive axle shaft for driving acontinuous ground-engaging track. The at least one drive axle shaft hasa second axis of rotation that is vertically offset from the first axisof rotation and substantially coaxial with a centerline of the drivewheel.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features and advantages willbecome apparent from the description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an example track work vehicle in the form of anagricultural tractor, which includes a high track drive system accordingto various embodiments of this disclosure;

FIG. 1A is a schematic perspective view of a drivetrain for the trackwork vehicle of FIG. 1, with a portion of each saddle assembly omittedfor clarity;

FIG. 2 is a perspective view of a differential gear case and a portionof the track drive system of the work vehicle of FIG. 1, whichillustrates the high track drive system coupled to the differential gearcase;

FIG. 3 is a partially exploded view of FIG. 2;

FIG. 4 is a cross-sectional view of the differential gear case and theportion of the track drive system of FIG. 2, taken along line 4-4 ofFIG. 2;

FIG. 5 is an exploded view of the high track drive system of FIG. 1;

FIG. 6 is a cross-sectional view of the differential gear case and theportion of the track drive system of FIG. 2, taken along line 6-6 ofFIG. 2; and

FIG. 7 is a perspective view of the high track drive system of FIG. 1.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

The following describes one or more example embodiments of the disclosedhigh track drive system, as shown in the accompanying figures of thedrawings described briefly above. Various modifications to the exampleembodiments may be contemplated by one of skill in the art.

As used herein, unless otherwise limited or modified, lists withelements that are separated by conjunctive terms (e.g., “and”) and thatare also preceded by the phrase “one or more of” or “at least one of”indicate configurations or arrangements that potentially includeindividual elements of the list, or any combination thereof. Forexample, “at least one of A, B, and C” or “one or more of A, B, and C”indicates the possibilities of only A, only B, only C, or anycombination of two or more of A, B, and C (e.g., A and B; B and C; A andC; or A, B, and C).

As used herein, the term “axial” refers to a direction that is generallyparallel to an axis of rotation, axis of symmetry, or centerline of acomponent or components. For example, in a cylinder or disc with acenterline and opposite, generally circular ends or faces, the “axial”direction may refer to the direction that generally extends in parallelto the centerline between the opposite ends or faces. In certaininstances, the term “axial” may be utilized with respect to componentsthat are not cylindrical (or otherwise radially symmetric). For example,the “axial” direction for a rectangular housing containing a rotatingshaft may be viewed as a direction that is generally in parallel withthe rotational axis of the shaft. Furthermore, the term “radially” asused herein may refer to a direction or a relationship of componentswith respect to a line extending outward from a shared centerline, axis,or similar reference, for example in a plane of a cylinder or disc thatis perpendicular to the centerline or axis. In certain instances,components may be viewed as “radially” aligned even though one or bothof the components may not be cylindrical (or otherwise radiallysymmetric). Furthermore, the terms “axial” and “radial” (and anyderivatives) may encompass directional relationships that are other thanprecisely aligned with (e.g., oblique to) the true axial and radialdimensions, provided the relationship is predominately in the respectivenominal axial or radial direction.

The following describes one or more example implementations of thedisclosed system for a high track drive system for a track work vehicle,as shown in the accompanying figures of the drawings described brieflyabove. Generally, the disclosed systems (and work vehicles in which theyare implemented) provide for elevating a drive axle shaft associatedwith a respective drive wheel to an elevation that is above an elevationassociated with a transmission output drive shaft or axle input shaft ofthe track work vehicle within a differential gear case associated withthe track work vehicle. This enables the drive wheels to be driven at ahigher elevation, while reducing a part count and weight associated withthe elevation change, and while also reducing cost and improvingproductivity of the work vehicle.

The following description relates to a work vehicle as a tractor.Discussion herein may sometimes focus on the example application of atractor having a high track drive system that is raises an axis ofrotation of a drive axle shaft. It should be noted, however, that thepresent disclosure is not limited to the track work vehicle, but rather,the high track drive system may be applied to a differential associatedwith any type of work vehicle.

In the example of the present disclosure, the high track drive system iscontained wholly within the differential gear case and includes a firstspur gear, a second spur gear, a bevel gear assembly and a bevel gearset. The first spur gear is coupled to the drive axle shaft, such as arear axle of the track work vehicle, and the first spur gear is coupledto the second spur gear. The first spur gear and the second spur gearare each supported for rotation by a gear housing. The second spur gearis coupled to the bevel gear assembly, and a bevel gear of the bevelgear assembly drives a ring gear. The ring gear, in turn, is coupled tothe bevel gear set, and drives the bevel gear set. The bevel gear set iscoupled to a pair of planetary gear sets, which in turn, are coupled tothe drive axle shafts that drive a pair of drive wheels.

As the second spur gear is stacked or coupled vertically above the firstspur gear for rotation thereby, the second spur gear cooperates with thebevel gear assembly to raise an elevation of the drive axle shafts suchthat the drive axle shafts are coaxial with a centerline of the drivewheels, but offset from an axis of rotation of the axle input shaft.

As noted above, the system described herein may be employed with respectto a variety of work vehicles, including various agricultural or otherwork vehicles. In certain embodiments, the described system may beimplemented with respect to a tractor. It will be understood, however,that the system disclosed herein may be used with various other workvehicles, such as a graders, excavators, etc. Referring to FIG. 1, atrack work vehicle, such as a tractor 10, is shown. The tractor 10includes a plurality of track systems 12, and a source of propulsion,such as an engine 20. The engine 20 supplies power to a transmission 22.As will be discussed, the transmission 22 transfers the power from theengine 20 to a suitable driveline 24 coupled to one or more of the tracksystems 12 of the tractor 10 to enable the tractor 10 to move. In oneexample, the engine 20 is an internal combustion engine, such as adiesel engine, that is controlled by an engine control module. It shouldbe noted that the use of an internal combustion engine is merelyexemplary, as the propulsion device can be a fuel cell, electric motor,a hybrid-electric motor, etc.

The tractor 10 also includes one or more pumps 26, which may be drivenby the engine 20 of the tractor 10. Flow from the pumps 26 may be routedthrough various control valves 28 and various conduits (e.g., flexiblehoses and lines) to control various components associated with thetractor 10. Flow from the pumps 26 may also power various othercomponents of the tractor 10. The flow from the pumps 26 may becontrolled in various ways (e.g., through control of the various controlvalves 28 and/or a controller 30 associated with the tractor 10). Aswill be discussed herein, flow from the pumps 26 may be routed throughone or more of the control valves 28 and various conduits to lubricate aportion of a differential gear case 48.

Generally, the controller 30 (or multiple controllers) may be provided,for control of various aspects of the operation of the tractor 10, ingeneral. The controller 30 (or others) may be configured as a computingdevice with associated processor devices and memory architectures, as ahard-wired computing circuit (or circuits), as a programmable circuit,as a hydraulic, electrical or electro-hydraulic controller, orotherwise. As such, the controller 30 may be configured to executevarious computational and control functionality with respect to thetractor 10 (or other machinery). In some embodiments, the controller 30may be configured to receive input signals in various formats (e.g., ashydraulic signals, voltage signals, current signals, and so on), and tooutput command signals in various formats (e.g., as hydraulic signals,voltage signals, current signals, mechanical movements, and so on). Insome embodiments, the controller 30 (or a portion thereof) may beconfigured as an assembly of hydraulic components (e.g., valves, flowlines, pistons and cylinders, and so on), such that control of variousdevices (e.g., pumps or motors) may be effected with, and based upon,hydraulic, mechanical, or other signals and movements.

The controller 30 may be in electronic, hydraulic, mechanical, or othercommunication with various other systems or devices of the tractor 10(or other machinery, such as an implement coupled to the tractor 10).For example, the controller 30 may be in electronic or hydrauliccommunication with various actuators, sensors, and other devices within(or outside of) the tractor 10, including various devices associatedwith the pumps 26, control valves 28, and so on. The controller 30 maycommunicate with other systems or devices (including other controllers,such as a controller associated with an implement) in various knownways, including via a CAN bus (not shown) of the tractor 10, viawireless or hydraulic communication means, or otherwise.

Various sensors may also be provided to observe various conditionsassociated with the tractor 10. In some embodiments, various sensors 34(e.g., pressure, flow or other sensors) may be disposed near the pumps26 and control valves 28, or elsewhere on the tractor 10. For example,sensors 34 observe a pressure associated with the pumps 26 and generatesensor signals based thereon.

The tractor 10 also includes a cab 40, which includes a human-machineinterface. The controller 30 receives input commands and interfaces withthe operator via the human-machine interface 42.

As illustrated in FIG. 1A, the tractor 10 includes a pair of the tracksystems 12 associated with a first or front axle assembly 44 of thetractor 10 in a forward driving direction D, and a pair of track systems12 associated with a transmission output shaft or drive shaft lower 49of the tractor 10 (only a portion of the track systems 12 areillustrated in FIG. 1A for clarity), which is coupled to an axle inputshaft 46 of a second or rear axle assembly 47. It should be noted thatwhile the tractor 10 is illustrated herein as comprising the pluralityof track systems 12, it will be understood that the tractor 10 caninclude any number of track systems 12, such as one or two. The pair oftrack systems 12 associated with the axle input shaft 46 of the tractor10 are each coupled to the differential gear case 48, which receivesinput torque from the transmission 22 via the axle input shaft 46.

In this example, with reference to FIG. 1, each of the track systems 12includes an undercarriage assembly 52, a saddle assembly 54, a track 56and a drive wheel 58. The drive wheel 58 is fastened to a drive axleshaft 72 and supported by an axle housing 60. The drive wheel 58 isannular, and defines an outer circumference 62 and a drive wheel hub 64.Generally, the drive wheel 58 is composed of a metal or metal alloy,which is cast as one integral piece. It will be understood, however,that the drive wheel 58 can be composed of multiple pieces that arewelded or otherwise fastened together. The outer circumference 62defines a plurality of track guides 66 (FIG. 2) substantiallycontinuously about a perimeter. In this example, the plurality of trackguides 66 comprises a plurality of slots, which are spaced substantiallyevenly about the perimeter of the outer circumference 62 to transfertorque from the drive wheel 58 to the track 56. Generally, the pluralityof track guides 66 each receive a respective one of a plurality of teeth(not shown) of the track 56 to drive the track 56 with the drive wheel58.

The drive wheel hub 64 couples the drive wheel 58 to the axle housing60. Generally, the drive wheel hub 64 defines one or more bores thatreceive a respective one of one or more mechanical fasteners to couplethe drive wheel 58 to an axle flange 70 associated with the axle housing60. With reference to FIG. 3, the axle housing 60 is substantiallycylindrical and substantially encloses the drive axle shaft 72 (FIG. 4),which is coupled to the axle flange 70. In one example, the drive axleshaft 72 is integrally formed with the drive axle shaft 72. The axleflange 70 extends from the axle housing 60 to enable the rotation of thedrive wheel 58 relative to the axle housing 60. With reference to FIG.4, the axle flange 70 is coupled to drive wheel hub 64 of the drivewheel 58 such that torque from the drive axle shaft 72 is transmitted tothe drive wheel 58 to drive the drive wheel 58. As will be discussedfurther herein, the drive axle shaft 72 is coupled to the differentialgear case 48 to receive input torque. The axle housing 60 also includesa flange 73, which couples the saddle assembly 54 to the axle housing60. As shown in FIG. 3, the flange 73 extends about a perimeter orcircumference of the axle housing 60 at an end of the axle housing 60that is substantially opposite an end of the axle housing 60 that isnear or adjacent to the axle flange 70.

With reference back to FIG. 1, in one example, the undercarriageassembly 52 is movably or pivotally coupled to the saddle assembly 54.The undercarriage assembly 52 is not coupled to the drive wheel 58.Generally, the undercarriage assembly 52 includes a plurality of firstidler wheels 74 and a plurality of bogey or second idler wheels 76,which are each supported for rotation relative to an undercarriage frame78. In this example, the undercarriage assembly 52 includes two pairs offirst idler wheels 74, and two pairs of second idler wheels 76. Each ofthe first idler wheels 74 and second idler wheels 76 cooperate to guidethe track 56 along the ground as it is driven by the drive wheel 58. Itshould be noted that this configuration of idler wheels 74, 76 is merelyexemplary, as any number and arrangement of idler wheels may beemployed.

The saddle assembly 54 includes a pair of arms 80 that each extendoutwardly from an annular base 82. With reference to FIG. 2, each of thearms 80 extend outwardly from the base 82 so as to be positioned onopposing sides of the drive wheel 58. The arms 80 each guide the track56 as the track 56 moves about the drive wheel 58. With reference toFIG. 3, the arms 80 may each include a flange 84, which couples therespective arm 80 to the base 82. The flange 84 may be curved tofacilitate placement of the arms 80 about the drive wheel 58.

The base 82 defines a central bore 86, which enables the saddle assembly54 to be removably coupled to the axle housing 60. By removably couplingthe saddle assembly 54 to the axle housing 60, the saddle assembly 54may be easily removed for maintenance or repairs. The base 82 defines aplurality of through-bores about a circumference of the bore 86, whichreceive a respective one of one or more mechanical fasteners to couplethe base 82 to the flange 73 of the axle housing 60.

With reference back to FIG. 1, the track 56 is continuous, and isreceived about a perimeter of the drive wheel 58 and the undercarriageassembly 52. Generally, the track 56 is tensioned about the drive wheel58 and the undercarriage assembly 52. In this example, the track 56 iscomposed of a polymeric material; however, the track 56 can be composedof a metal or metal alloy. An exterior surface of the track 56 includesa plurality of projections or treads (not shown), which project from theexterior surface to engage the terrain over which the tractor 10travels. An interior surface includes the plurality of teeth (not shown)that extend outwardly from the interior surface to engage the drivewheel 58, the first idler wheels 74 and the second idler wheels 76 tomove or drive the track 56 about the perimeter of the drive wheel 58 andthe undercarriage assembly 52.

With reference to FIG. 2, the pair of track systems 12 associated withthe axle input shaft 46 are each coupled to the differential gear case48. The differential gear case 48 is coupled to a frame of the tractor10. The differential gear case 48 receives input torque from thetransmission 22 via the axle input shaft 46. The differential gear case48 includes a pair of final drive gear sets or planetary gear sets 100and a high track drive system 102. The planetary gear sets 100 are eachgenerally received within a differential case or housing 104 of thedifferential gear case 48, and the high track drive system 102 is alsoreceived within the housing 104. The high track drive system 102 islubricated by a lubrication fluid supplied by a lubrication system 200,as will be discussed further herein.

Generally, with reference to FIG. 3, the planetary gear sets 100 receiveas input torque from the high track drive system 102. The planetary gearsets 100 increase the received torque and transmit the increased torqueto the drive axle shaft 72. In this example, each of the planetary gearsets 100 include three planet gears 106, which are driven by a sun gear108 about a ring gear 110. The sun gear 108 is coupled to a sun inputshaft 112. With reference to FIG. 4, a planetary carrier 114 supportsthe planet gears 106 and is coupled to an end of the drive axle shaft72.

As shown in FIG. 4, an axis of rotation R of the drive axle shaft 72 iscoaxial with a centerline C of the drive wheel 58, and is offset from anaxis of rotation R2 of the axle input shaft 46. The high track drivesystem 102 receives the input torque from the axle input shaft 46 andraises the input torque to an axis of rotation R3, which is generallytransverse to and substantially intersects the axis of rotation R of thedrive axle shaft 72. The high track drive system 102 enables the driveaxle shafts 72 to be driven at an elevation E, which is above or greaterthan an elevation E1 of the axle input shaft 46 of the tractor 10 (FIG.1). A distance D1 is defined between the elevation E and the elevationE1, which is greater than zero. Thus, the axis of rotation R of thedrive axle shaft 72 is vertically offset from the axis of rotation R2 ofthe axle input shaft 46.

With reference to FIG. 5, the high track drive system 102 is shown ingreater detail. The high track drive system 102 includes a gear housing120, a first spur gear 122, a second spur gear 124, a bevel gearassembly 126, a ring gear 128 and a bevel gear set 130. The gear housing120 is composed of a metal or metal alloy, and may composed of multiplepieces that are cast, machined, stamped, etc. and assembled to definethe gear housing 120. The gear housing 120 supports the first spur gear122, the second spur gear 124 and the bevel gear 160 for rotation. Thegear housing 120 also supports a portion of the axle input shaft 46. Thegear housing 120 includes main housing 132 and a back plate 134. Themain housing 132 has a first side 136 and a second, opposite side 138,with a first chamber 140 and a second chamber 142 defined through themain housing 132 from the first side 136 to the second side 138. Theback plate 134 is coupled to the second side 138, via one or moremechanical fasteners, to enclose the gear housing 120.

With reference to FIG. 6, on the first side 136, the first chamber 140receives the axle input shaft 46, which is supported for rotation by oneor more bearings contained within the first chamber 140. On the secondside 138, the first chamber 140 receives the first spur gear 122. Thesecond chamber 142 is spaced vertically apart from the first chamber140. On the first side 136, the second chamber 142 receives the bevelgear assembly 126, which is supported for rotation by one or morebearings contained within the second chamber 142. On the second side138, the second chamber 142 receives the second spur gear 124, which isrotatably coupled to the first spur gear 122. As will be discussed, thegear housing 120 also cooperates with the lubrication system 200associated with the high track drive system 102.

With reference back to FIG. 5, the first spur gear 122 includes acentral bore 144. A spline may be defined on an interior of the bore 144for coupling to a spline 46 a of the axle input shaft 46 to the firstspur gear 122. A nut, which threadably engages a portion of the axleinput shaft 46 near the spline 46 a, may be employed to further couplethe axle input shaft 46 to the first spur gear 122. The first spur gear122 is coupled to the axle input shaft 46 such that the first spur gear122 rotates with or is driven by the axle input shaft 46. The first spurgear 122 is composed of a metal or metal alloy, and is stamped,machined, cast, etc. The first spur gear 122 has a diameter D2, which isdifferent than a diameter D3 of the second spur gear 124. In thisexample, the diameter D2 is greater than the diameter D3. The first spurgear 122 defines a plurality of gear teeth 148 about a perimeter orouter circumference of the first spur gear 122. The plurality of gearteeth 148 meshingly engage with a plurality of gear teeth 150 of thesecond spur gear 124.

The second spur gear 124 defines the plurality of gear teeth 150 about aperimeter or outer circumference of the second spur gear 124. Theplurality of gear teeth 150 meshingly engage with a plurality of gearteeth 148 such that the first spur gear 122 drives the second spur gear124. The second spur gear 124 defines a central bore 152. A spline maybe defined on an interior of the bore 152 for coupling to a spline 154of the bevel gear assembly 126. A bolt and washer 156 may be receivedwithin the bore 152 to assist in coupling the bevel gear assembly 126 tothe second spur gear 124. The second spur gear 124 is composed of ametal or metal alloy, and is stamped, machined, cast, etc. The secondspur gear 124 is coupled to the bevel gear assembly 126 to drive thebevel gear assembly 126.

The bevel gear assembly 126 includes a pinion shaft 158 and a bevel gear160. The pinion shaft 158 and the bevel gear 160 are each composed of ametal or metal alloy, and are each stamped, machined, cast, etc. Thepinion shaft 158 may be formed discrete from the bevel gear 160, andcoupled together via a suitable post processing step or may beintegrally formed. The pinion shaft 158 includes the spline 154. Thepinion shaft 158 is received within the second chamber 142, and issupported for rotation within the second chamber 142 by the one or morebearings. An end of the pinion shaft 158 opposite the spline 154 iscoupled to the bevel gear 160.

The bevel gear 160 generally extends beyond the second chamber 142 ofthe gear housing 120 (FIG. 6). The bevel gear 160 defines a plurality ofbevel gear teeth 162 about a perimeter or outer circumference of thebevel gear 160. The bevel gear teeth 162 meshingly engage with aplurality of bevel gear teeth 164 defined on the ring gear 128.Generally, each of the bevel gear teeth 162, 164 are spiral bevel gearteeth, however, the bevel gear teeth 162, 164 may comprise hypoid bevelgear teeth. The bevel gear 160 drives the ring gear 128.

The ring gear 128 includes a first face 166 opposite a second face 168and a central bore 170. The ring gear 128 is composed of a metal ormetal alloy, and is stamped, machined, cast, etc. The plurality of bevelgear teeth 164 are defined on the first face 166. The plurality of bevelgear teeth 164 are defined about the first face 166 such that theplurality of bevel gear teeth 164 surround or circumscribe the bore 170.The second face 168 is substantially planar, and is coupled to the bevelgear set 130. A portion of the bevel gear set 130 is also receivedthrough the bore 170. The rotation of the ring gear 128 drives the bevelgear set 130, which transfers torque to the sun input shafts 112 of theplanetary gear sets 100.

The bevel gear set 130 includes a second set of three planet gears 174,a differential side gear 176 and a carrier housing 178. A plurality ofteeth may be defined about the second face 168 of the ring gear 128 tobe observable by a sensing device, such as a speed sensor, for example.With reference to FIG. 4, the second set of three planet gears 174 arecoupled to the carrier housing 178. The movement of the carrier housing178 drives the second set of planet gears 174. The second set of planetgears 174 each meshingly engage with the differential side gear 176. Thedifferential side gear 176 is coupled to each of the sun input shafts112. The movement of the second set of planet gears 174 drives thedifferential side gear 176, which in turn drives each of the sun inputshafts 112.

The lubrication system 200 provides oil or other lubrication fluid tothe high track drive system 102. In this example, the lubrication system200 receives the oil from the one or more pumps 26 associated with thetractor 10 via one or more conduits (FIG. 1A). The lubrication system200 cooperates with the gear housing 120 to lubricate the first spurgear 122, the second spur gear 124, the bevel gear assembly 126 and theaxle input shaft 46. With reference to FIG. 6, the lubrication system200 includes a clean oil reservoir 202, a quill lubrication tube orfirst oil conduit 204 and a spiral bevel lubrication tube or second oilconduit 206.

The clean oil reservoir 202 receives the oil from the pumps 26 and/orcontrol valves 28 of the tractor 10 via one or more conduits (FIG. 1A).The clean oil reservoir 202 is continuously filled during the operationof the tractor 10, and once the clean oil reservoir 202 is filled withoil, the clean oil exits the clean oil reservoir 202 through the firstoil conduit 204. The clean oil reservoir 202 is isolated from theremainder of the differential gear case 48 via one or more sealingelements, such as O-rings 202 a, 202 b.

The first oil conduit 204 is tubular, and directs the clean oil from theclean oil reservoir 202 to the gear housing 120. The first oil conduit204 includes an inlet 204 a in fluid communication with the clean oilreservoir 202 and an outlet 204 b. The outlet 204 b is positionedsubstantially over the gear housing 120 within the differential gearcase 48. The clean oil exits the first oil conduit 204 via the outlet204 b and enters into the gear housing 120 via a lubrication bore 208defined in the gear housing 120. The lubrication bore 208 is in fluidcommunication with the second chamber 142 and is also in fluidcommunication with the first chamber 140. The clean oil received intothe gear housing 120 via the lubrication bore 208 fills the gear housing120 with the clean oil until the level of oil in the gear housing 120reaches a predefined level. The back plate 134 retains the oil withinthe gear housing 120, and a seal 210 coupled to the first chamber 140further retains the oil within the first chamber 140 to enable the gearhousing 120 to fill with oil.

Once the oil in the gear housing 120 reaches the predefined level, theoil exits the gear housing 120 at point A and B near the bevel gearassembly 126. Air pressure in the gear housing 120 also exits via ahollow chamber 212 defined within the axle input shaft 46 and the driveshaft lower 49. The air flows through the axle input shaft 46 and thedrive shaft lower 49 and returns to the transmission 22 (FIG. 1A) toequalize air pressure with atmosphere.

The second oil conduit 206 is in fluid communication with the pumps 26and/or control valves 28 of the tractor 10 via one or more conduits toreceive oil or other lubricating fluid. In this example, the second oilconduit 206 is distinct or separate from the clean oil reservoir 202 andthe first oil conduit 204. The second oil conduit 206 receives clean oilat an inlet 206 a. The second oil conduit 206 is tubular and directs theclean oil along the first side 136 of the gear housing 120. Downstreamfrom the inlet 206 a and along the first side 136 of the gear housing120 adjacent to or near the second chamber 142, the second oil conduit206 defines an outlet portion 214. The outlet portion 214 issubstantially U-shaped so as to surround at least a portion of the bevelgear 160. The outlet portion 214 includes a plurality of holes 216,which are spaced apart along the second oil conduit 206 and orientatedto direct oil onto a face 160 a of the bevel gear 160, the bevel gearteeth 162 of the bevel gear 160 and onto the bevel gear teeth 164 of thering gear 128. Stated another way, the second oil conduit 206 definesthe plurality of holes 216 through the second oil conduit 206 to supplyoil to the bevel gear assembly 126. In one example, the outlet portion214 includes about 4 holes having about a 1.5 millimeter (mm) to about a2.0 millimeter (mm) diameter.

With reference to FIG. 3, in order to assemble the differential gearcase 48, the high track drive system 102 may be assembled and coupled tothe differential gear case 48. In one example, with reference to FIG. 5,with the bevel gear 160 coupled to the pinion shaft 158, the pinionshaft 158 is inserted through the second chamber 142 and coupled to thesecond spur gear 124. The first spur gear 122 is coupled to the firstchamber 140, and the back plate 134 is coupled to the gear housing 120to retain the first spur gear 122, the second spur gear 124 and the oilor lubrication fluid within the gear housing 120. The ring gear 128 iscoupled to the assembled bevel gear set 130, and the ring gear 128 ispositioned such that the bevel gear teeth 162, 164 meshingly engage.

With reference to FIG. 6, with the high track drive system 102assembled, the high track drive system 102 is positioned within thedifferential gear case 48. The axle input shaft 46 is inserted into thedifferential gear case 48 and coupled to the first spur gear 122. Withthe clean oil reservoir 202 defined within the differential gear case48, the O-rings 202 a, 202 b may be coupled to the differential gearcase 48 to seal the clean oil reservoir 202 from the environment. Thefirst oil conduit 204 may be coupled to the differential gear case 48such that the outlet 204 b is aligned with the lubrication bore 208 ofthe gear housing 120. The second oil conduit 206 may be coupled to thedifferential gear case 48, and positioned such that the outlet portion214 surrounds a portion of the face 160 a of the bevel gear 160.

With reference to FIG. 4, with the planetary gear sets 100 assembled,the sun input shafts 112 are each coupled to the differential side gear176 of the bevel gear set 130. The drive axle shafts 72 are each coupledto a respective one of the planetary carriers 114 of the planetary gearsets 100, and the axle housing 60 is coupled to the planetary gear sets100 about the drive axle shafts 72. With reference to FIG. 3, arespective one of the saddle assemblies 54 is coupled to a respectiveone of the axle housings 60, and a respective one of the drive wheels 58is coupled to a respective one of the axle flanges 70. With reference toFIG. 1, a respective one of the undercarriage assemblies 52 is coupledto a respective one of the saddle assemblies 54, and a respective one ofthe tracks 56 is positioned about a respective one of the drive wheels58.

With reference to FIG. 7, when the tractor 10 is in motion, torque istransmitted from the axle input shaft 46 into the high track drivesystem 102. The torque from the axle input shaft 46 drives the firstspur gear 122, which in turn drives the second spur gear 124. The secondspur gear 124 drives the bevel gear assembly 126, and the bevel gear 160drives the ring gear 128. The ring gear 128 drives the bevel gear set130. With reference to FIG. 4, the bevel gear set 130 drives theplanetary gear sets 100, which in turn drive the drive axle shafts 72,and thus, the drive wheels 58. The axis of rotation R of the drive axleshafts 72 is coaxial with the centerline C of the drive wheels 58, whichis spaced apart from the axis of rotation R2 of the axle input shaft 46by the distance D1. Thus, the high track drive system 102 enables thedrive axle shafts 72 and the drive wheels 58 to be driven at theelevation E that is greater than the elevation E1 of the axle inputshaft 46.

In addition, while the tractor 10 is in operation, with reference toFIG. 6, the pumps 26 and/or control valves 28 supply clean oil to theclean oil reservoir 202. Once filled, the clean oil exits the clean oilreservoir 202 and flows through the first oil conduit 204 to enter thegear housing 120 via the lubrication bore 208. The oil fills the gearhousing 120 until the oil reaches the predefined level and exits throughthe point A and/or point B. In addition, the second oil conduit 206supplies oil to the face 160 a of the bevel gear 160 via the holes 216.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

The description of the present disclosure has been presented forpurposes of illustration and description, but is not intended to beexhaustive or limited to the disclosure in the form disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of thedisclosure. Explicitly referenced embodiments herein were chosen anddescribed in order to best explain the principles of the disclosure andtheir practical application, and to enable others of ordinary skill inthe art to understand the disclosure and recognize many alternatives,modifications, and variations on the described example(s). Accordingly,various embodiments and implementations other than those explicitlydescribed are within the scope of the following claims.

What is claimed is:
 1. A track drive system for a work vehicle having acontinuous ground-engaging track, the track drive system comprising: afirst gear coupled to an axle input shaft defining a first axis ofrotation; a second gear coupled to the first gear; a bevel gear assemblycoupled to the second gear and defining a third axis of rotation; abevel gear set coupled to at least one planetary gear set of adifferential of the work vehicle; at least one drive axle shaft coupledto the at least one planetary gear set and defining a second axis ofrotation; and a drive wheel for driving the continuous ground-engagingtrack, the drive wheel having a centerline; wherein the second axis ofrotation of the at least one drive axle shaft is vertically offset fromthe first axis of rotation of the first gear and substantially coaxialwith the centerline of the drive wheel and intersects the third axis ofrotation of the bevel gear assembly.
 2. The track drive system of claim1, wherein the bevel gear assembly includes a shaft and a bevel gear,and the shaft is coupled to the second gear and extends substantiallyalong the third axis of rotation.
 3. The track drive system of claim 2,wherein the bevel gear is coupled to a ring gear, and the ring gear iscoupled to the bevel gear set to drive the bevel gear set and to drivethe at least one planetary gear set.
 4. The track drive system of claim1, further comprising a gear housing having a first side and a secondside, with a first chamber and a second chamber each defined from thefirst side to the second side, and the first gear and the second gearare coupled to the second side.
 5. The track drive system of claim 4,wherein the first gear is coupled to the first chamber, and the axleinput shaft is received into the first chamber at the first side tocouple the axle input shaft to the first gear.
 6. The track drive systemof claim 4, wherein the second gear is coupled to the second chamber,and the bevel gear assembly is received into the second chamber at thefirst side to couple the bevel gear assembly to the second gear.
 7. Thetrack drive system of claim 1, further including a gear housing suppliedwith lubrication through a first conduit of a lubrication system.
 8. Thetrack drive system of claim 7, wherein the bevel gear assembly issupplied with lubrication through a second conduit of the lubricationsystem having an outlet portion with a plurality of holes.
 9. The trackdrive system of claim 1, wherein the at least one drive axle issubstantially enclosed by at least one axle housing shaft and at leastone saddle that supports the continuous ground-engaging track.
 10. Atrack drive system for a work vehicle having a continuousground-engaging track, the track drive system comprising: a first gearcoupled to an axle input shaft defining a first axis of rotation; asecond gear coupled to the first gear; a bevel gear assembly coupled tothe second gear and defining a third axis of rotation; a bevel gear setcoupled to at least one planetary gear set of a differential of the workvehicle; a ring gear coupled to the bevel gear set and to the bevel gearassembly; at least one drive axle shaft coupled to the at least oneplanetary gear set and defining a second axis of rotation; and a drivewheel for driving the continuous ground-engaging track, the drive wheelhaving a centerline; wherein the second axis of rotation of the at leastone drive axle shaft is vertically offset from the first axis ofrotation of the first gear and substantially coaxial with the centerlineof the drive wheel and intersects the third axis of rotation of thebevel gear assembly.
 11. The track drive system of claim 10, wherein thebevel gear assembly includes a shaft and a bevel gear, and the shaft iscoupled to the second gear and extends substantially along the thirdaxis of rotation.
 12. The track drive system of claim 10, furthercomprising a gear housing having a first side and a second side, with afirst chamber and a second chamber each defined from the first side tothe second side, and the first gear and the second gear are coupled tothe second side.
 13. The track drive system of claim 12, wherein thefirst gear is coupled to the first chamber, and the axle input shaft isreceived into the first chamber at the first side to couple the axleinput shaft to the first gear.
 14. The track drive system of claim 13,wherein the second gear is coupled to the second chamber, and the bevelgear assembly is received into the second chamber at the first side tocouple the bevel gear assembly to the second gear.
 15. The track drivesystem of claim 10, further including a gear housing supplied withlubrication through a first conduit of a lubrication system.
 16. Thetrack drive system of claim 15, wherein the bevel gear assembly issupplied with lubrication through a second conduit of the lubricationsystem having an outlet portion with a plurality of holes.
 17. The trackdrive system of claim 10, wherein the at least one drive axle issubstantially enclosed by at least one axle housing shaft and at leastone saddle that supports the continuous ground-engaging track.
 18. Atrack drive system for a work vehicle having a continuousground-engaging track, the track drive system comprising: a first gearcoupled to an axle input shaft defining a first axis of rotation; asecond gear coupled to the first gear; a bevel gear assembly having ashaft and a bevel gear, the shaft coupled to the second gear andextending substantially along a third axis of rotation; a bevel gear setcoupled to at least one planetary gear set of a differential of the workvehicle; a ring gear coupled to the bevel gear set and to the bevelgear; at least one drive axle shaft coupled to the at least oneplanetary gear set and defining a second axis of rotation; and a drivewheel for driving the continuous ground-engaging track, the drive wheelhaving a centerline; wherein the second axis of rotation of the at leastone drive axle shaft is vertically offset from the first axis ofrotation of the first gear and substantially coaxial with the centerlineof the drive wheel and intersects the third axis of rotation of thebevel gear assembly.
 19. The track drive system of claim 18, furtherincluding a gear housing supplied with lubrication through a firstconduit of a lubrication system; wherein the bevel gear assembly issupplied with lubrication through a second conduit of the lubricationsystem having an outlet portion with a plurality of holes.
 20. The trackdrive system of claim 18, wherein the at least one drive axle issubstantially enclosed by at least one axle housing shaft and at leastone saddle that supports the continuous ground-engaging track.